In Vitro Quantitative and Qualitative Analyses of Different Concentrations of GNRH on Cattle Embryos (original) (raw)
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Theriogenology, 2006
This study evaluates the in vitro developmental competence of oocytes collected by ovum pick up (OPU) from sheep treated with GnRH antagonists (GnRHa) and high doses of FSH. Eighteen Sarda ewes were treated with progestagen sponges (day 0). On day 7, 10 ewes received 3 mg of GnRHa s.c., while 8 served as control receiving saline. On day 10, all animals were treated with 96 IU of ovine FSH in four equal doses given i.m. every 12 h. We monitored follicular development by ultrasonography, twice daily from day 7 to 11, and found that GnRHa induced a significant increase in the number of total follicles in 72 h (11.7 AE 0.9 to 21 AE 2.4, r 2 = 0.598, P < 0.0001), while this number remained stable in control sheep. We found that FSH induced a significant rise in the number of follicles in both groups; but always higher (P < 0.05) in GnRHa treated sheep, confirming that GnRHa enhances ovarian response to exogenous FSH stimulation. Twelve hours after the last FSH dose, oocytes were collected by OPU. Recovery percentage, morphological quality, ability to resume meiosis, fertilization and cleavage were similar in oocytes from treated and untreated sheep. However, the final blastocysts output was lower in GnRHa group (10.1% versus 27.4% in control group; P < 0.05). In addition, re-expansion rates after vitrification, thawing and in vitro culture were www.journals.elsevierhealth.com/periodicals/the Theriogenology 65 (2006) 1099-1109
Animal Review, 2016
This study was conducted to evaluate the efficacy of reducing GnRH dose on the formation of ovulation and conception, and sizes of the ovarian structures following an Ovsynch program in lactating cows. The cows were allocated randomly to two treatment groups (full dose; FD, n=20 and half dose; HD, n=20). Cows in the FD group were treated with 10.5 µg buserelin acetate on day 0, with 0.150 mg D-cloprostenol 7 d later and with 10.5 µg buserelin acetate 2 d later. Estrous cycles in HD group were synchronized using the same scheme as FD-treated cows, but the dose of buserelin acetate was reduced to 5.25 µg at both GnRH administration times. Ovarian structures were monitored by ultrasound with a 6-8 MHz linear trans-rectal probe on days 0, 7, 9, 10, and 11. Cows were inseminated at the 16-20 h after second GnRH administration. No significant differences were observed in the dominant or ovulatory follicle diameters in FD and HD groups. Ovulation incidence from second GnRH injection by the 24 hour after fixed-time AI did not differ between FD (85 %) and HD (90 %) groups. Also, the conception percentages did not differ statistically between the HD (50%) and FD (40 %) groups.
Journal of Dairy Science, 2003
Two experiments examined effects of GnRH administered within 3 h after onset of estrus (OE) on ovulation and conception in dairy cows. In experiment 1, 46 cows received either saline, 250 μg of GnRH, or 10 μg of the GnRH analogue, Buserelin. Cows were observed for estrus, blood samples were collected, and ovulations were monitored by ultrasound. In controls, 76% of cows had intervals from estrus to ovulation of ≤ 30 h and 24% had intervals > 30 h. Treatment with either GnRH or GnRH analogue (data combined) increased magnitude of LH surges and decreased intervals from estrus to LH surge or to ovulation. Treated cows all ovulated ≤ 30 h after OE. Among control cows, plasma estradiol concentrations before estrus correlated positively with amplitudes of LH surges. Higher plasma progesterone was observed in the subsequent estrous cycle in GnRHtreated cows compared to control cows with delayed ovulations. Experiment 2 included 152 primiparous and 211 multiparous cows in summer and winter. Injection of GnRH analogue at OE increased conception rates (CR) from 41.3 to 55.5% across seasons. In summer, GnRH treatment increased CR from 35.1 to 51.6%. Across seasons, GnRH increased CR from 36.0 to 61.5% in cows with lower body condition at insemination and GnRH increased CR (63.2 vs. 42.2%) in primiparous cows compared to controls. Use of GnRH eliminated differences in CR for cows inseminated early or late relative to OE and increased CR in cows having postpartum reproductive disorders. In conclusion, GnRH at onset of estrus increased LH surges, prevented delayed ovulation, and may increase subsequent progesterone concentrations. Treatments with GnRH increased conception in primiparous cows, during summer, and in cows with lower body condition.
Reproductive responses of cattle to GnRH agonists
Animal Reproduction Science, 2000
Corresponding author. M.J. D'Occhio . 0378-4320r00r$ -see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 3 7 8 -4 3 2 0 0 0 0 0 0 7 8 -6 ( ) M.J. D'Occhio et al.r Animal Reproduction Science 60-61 2000 433-442 434 bioimplants have been incorporated into new multiple ovulation and embryo transfer protocols that allow control of the time of ovulation subsequent to superstimulation of ovarian follicular growth with FSH. In these protocols, the endogenous surge release of LH is blocked by treatment with agonist and ovulation is timed by injection of exogenous LH, allowing fixed-time AI. It can be concluded from recent studies that GnRH agonist bioimplants have considerable potential for both pro-fertility and anti-fertility applications in cattle. It is likely that commercial bioimplants will be available within the next 3 to 5 years. q
Fertilization in vitro of rat oocytes undergoing maturation in response to a GnRH analogue
Reproduction, 1987
Oocytes were exposed to GnRHa to induce their maturation both in vivo, by administration of the hormone to hypophysectomized rats, and in vitro, in cultures of intact ovarian follicles. Mature oocytes obtained under both these conditions were then exposed in vitro to a sperm suspension for fertilization. Fertilization of control groups of oocytes, isolated from intact or hypophysectomized PMSG-primed hCG-induced ovulators, was 88\m=.\3\ m=+-\3\m=.\3%(n = 331) and 90\m=.\0\ m=+-\2\m=.\8%(n = 427), respectively, as compared to 82\m=.\8\ m=+-\3\m=.\2%(n = 413) for oocytes isolated from hypophysectomized PMSG-primed GnRHa-induced ovulators. Fertilization rate in oocytes treated by GnRHa in vitro was 78\m=.\5\ m=+-\ 3 \ m=. \ 1%(n = 247) as compared to 79\m=.\3\ m=+-\ 4\m=.\1% (n = 261) in LH-treated oocytes. These results demonstrate that fertilizability of oocytes undergoing maturation in response to GnRHa is similar to that of oocytes induced to mature by LH. No differences could be detected in the proportions of abnormal oocytes (polyspermic, fragmented and dead) and the zygotes obtained after fertilization of GnRHaor LH-treated oocytes showed similar ability to cleave.
2013
Received: Accepted: Online: The present study was conducted at Sheep and Goat Research Station, Bahauddin Zakariya University, Multan. The objectives of this study were to investigate the effects of GnRH analogue (Dalmarelin) treatment on Day 12 of pregnancy on ovarian function, plasma hormone concentrations and embryo development to improve litter size. Sixteen Lohi sheep 3-4 years old, weighing 44±0.4 kg (Mean ± S.E.M) were selected. The daily feed/ration was hay, seasonal fodder, tree looping and 250g concentrate per sheep. Sheep were mated to ram at synchronized estrus by two i/m injections of 2ml PGF2α analogue (Dalmazin) given at 11 days apart. These animals were divided into two treatment groups (8/group) through random stratification by body weight. Animals were injected an either saline (group I) or 2ml GnRH (group II) on Day 12 post-mating. The blood samples were collected from jugular venipuncture (3ml) with a disposable syringe from 1 hour before and 0, 2, 4, 6, 8, 24, 4...
Animal Reproduction Science, 1997
A model designed to mimic the action of LH in preovulatory follicle development was evaluated. The model involved treatment of ewes with GnRHa (50 micrograms kg-1 24 h-1; GnRHa) at the time of luteal regression followed by exogenous LH administered as a series of bolus injections of varying frequency and amplitude. Ovarian responses to this regimen were compared to data derived from the same animals during a normal follicular phase. In experiment 1 four ewes with an autotransplanted ovary were treated with GnRHa followed by hourly LH (2.5 micrograms NIH-oLH-S25 i.v.) for 60 h at which time a further bolus of LH (25 micrograms i.v.) was given to mimic the LH surge. Plasma FSH profiles and the pattern and rate of secretion of oestradiol, inhibin, androstenedione and testosterone by the ovary in normal and GnRHa treated ewes were similar, but ovulation did not occur following the induced follicular phase. Experiment 2 examined the ability of a revised LH regimen to induce ovulation in normal intact ewes. Ewes (n = 11) were treated with GnRHa at the time of luteal regression followed by LH injections (1.25 micrograms i.v.) administered every 3 h for 12 h, every 2 h for the next 12 h and every hour for the following 36 h (3,2,1 regimen). After 60 h of LH injections the animals received an 8 h infusion of oLH (25 micrograms min-1) designed to mimic the pre-ovulatory LH surge. This treatment resulted in normal follicular phase patterns of LH and FSH and had no effect on the incidence (100%) or number (1.6 +/- 0.1) of ovulations when compared to a normal cycle (100% and 1.8 +/- 0.2). Experiment 3 examined the pattern of ovarian follicular development and hormone secretion stimulated by the 3,2,1 LH regimen in ewes with autotransplanted ovaries (n = 8). The LH regimen stimulated normal pre-ovulatory follicular development (normal 1.4 +/- 0.2; induced 1.6 +/- 0.2) and a normal pattern of ovarian oestradiol and androstenedione secretion. Pulse analysis showed, however, that baseline steroid secretion was lower in induced animals during the late follicular phase reflecting lower baseline LH at this stage. We conclude that administration of a GnRHa at the time of luteal regression in conjunction with frequent low amplitude pulses of exogenous LH induce follicular and hormonal patterns that closely mimic those observed following normal luteal regression and that this regimen represents a useful model to study the role of LH in the control of follicular selection.
Influence of GnRH and its timing of application on the fertility of artificially inseminated dairy cows synchronized with double doses of PGF2α” (Atena Editora), 2023
The objective of this research was to analyze the effect of GnRH applied at the beginning of estrus or in artificial insemination, considering that low fertility problems in dairy herds is one of the factors that most affects production and profitability levels. 146 Jersey cows with 2.2 lactations, 40.2 days in milk and 2.8 of body condition were used, which were synchronized with two applications of prostaglandin F2α, at the beginning of estrus, they were randomly assigned to one of three treatments, T1: GnRH/I.A; n = 51, T2: GnRH/SD; n=49; and T3: Without GnRH, the pregnancy percentage was analyzed by logistic regression with the glm procedure with the R software. The percentage of pregnancies was not different between treatments, with values of 45, 59 and 46 respectively, possibly because in this exploitation, nutrition, management, health and heat detection are optimal. Therefore, it is concluded that in the conditions in which this research was carried out, GnRH did not improve fertility.